@Damien_C , @Leo_Visser, @Pagee , @strothei , @MuttakiNl , @rajbhansali , @dram , @stylechild , a problem similar to yours was reported by another user. He found that it disappeared after he completely shut down his Mac and restarted it. (Not just a restart; not put it to sleep and woke it up; but a hard shutdown.)
Could you try that and let us know if your problem resolved?